The cosmetic whitening of the teeth has been a prevalent concern of the modern consumer. Traditionally abrasives and bleaches have been used to effectuate the desired whitening. One of the agents used by dentists for in-office cosmetic bleaching has been hydrogen peroxide. While hydrogen peroxide is a very safe chemical in dilute quantities it is very caustic and will cause severe tissue damage at higher concentrations. Thus, its use has heretofore been limited to controlled use in the dentist's office. Recently, dentists have attempted to bleach teeth using a vacuformed mouthpiece which fits over the teeth and adjacent tissue with a dilute hydrogen peroxide gel (11/2% hydrogen peroxide). the technique is laudable, the continued exposure of the mucous membranes of the mouth to hydrogen peroxide oft en seems to result in oral irritation which necessitates discontinuation of the treatment. Therefore a need exists for a means for protecting the gum tissues while permitting hydrogen peroxide to contact the teeth.